A Raman study of temperature dependence of phonons near the λ -phase transitions in ammonium halides

ARI ◽  
1998 ◽  
Vol 51 (1) ◽  
pp. 77-80 ◽  
Author(s):  
H. Yurtseven ◽  
W. F. Sherman
Keyword(s):  
Phase Transitions ◽  
Temperature Dependence ◽  
Ammonium Halides ◽  
Raman Study

scholarly journals Temperature-Dependent Evolution of Raman Spectra of Methylammonium Lead Halide Perovskites, CH3NH3PbX3 (X = I, Br)

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 626 ◽  
Author(s):  
Kousuke Nakada ◽  
Yuki Matsumoto ◽  
Yukihiro Shimoi ◽  
Koji Yamada ◽  
Yukio Furukawa
Keyword(s):  
Phase Transitions ◽  
Temperature Dependence ◽  
Temperature Dependent ◽  
High Power Conversion Efficiency ◽  
Perovskite Materials ◽  
Hybrid Perovskite ◽  
Temperature Ranges ◽  
Raman Study ◽  
Halide Perovskites ◽  
Motional Narrowing

We present a Raman study on the phase transitions of organic/inorganic hybrid perovskite materials, CH3NH3PbX3 (X = I, Br), which are used as solar cells with high power conversion efficiency. The temperature dependence of the Raman bands of CH3NH3PbX3 (X = I, Br) was measured in the temperature ranges of 290 to 100 K for CH3NH3PbBr3 and 340 to 110 K for CH3NH3PbI3. Broad ν1 bands at ~326 cm−1 for MAPbBr3 and at ~240 cm−1 for MAPbI3 were assigned to the MA–PbX3 cage vibrations. These bands exhibited anomalous temperature dependence, which was attributable to motional narrowing originating from fast changes between the orientational states of CH3NH3+ in the cage. Phase transitions were characterized by changes in the bandwidths and peak positions of the MA–cage vibration and some bands associated with the NH3+ group.

Spectroscopic study of [Me(NH3)6]X2 compounds. I-Raman study of phase transitions in [Ni(NH3)6](ClO4)2 and [Ni(ND3)6](ClO4)2

1977 ◽  
Vol 6 (3) ◽  
pp. 130-134 ◽  
Author(s):  
J. A. Janik ◽  
T. Sarga ◽  
J. M. Janik ◽  
G. Pytasz ◽  
J. Sokotowski
Keyword(s):  
Phase Transitions ◽  
Spectroscopic Study ◽  
Raman Study

Raman study of low temperature phase transitions in the cubic perovskite CH3NH3PbCI3

1998 ◽  
Vol 64 (4) ◽  
pp. 179-190 ◽  
Author(s):  
A. Maaej ◽  
M. Bahri ◽  
Y. Abid ◽  
N. Jaidane ◽  
Z. B. Lakhdar ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Temperature Phase ◽  
Raman Study ◽  
Low Temperature Phase

A high pressure Raman study of 9‐hydroxyphenalenone and pressure‐induced phase transitions

1987 ◽  
Vol 87 (6) ◽  
pp. 3587-3590 ◽  
Author(s):  
A. Jayaraman ◽  
G. A. Kourouklis ◽  
R. C. Haddon
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Raman Study

Molecular Motions and Phase Transitions in Solid CH3NH3PbX3 (X = C1, Br, I) as Studied by NMR and NQR

1991 ◽  
Vol 46 (3) ◽  
pp. 240-246 ◽  
Author(s):  
Qiang Xu ◽  
Taro Eguchi ◽  
Hirokazu Nakayama ◽  
Nobuo Nakamura ◽  
Michihiko Kishita
Keyword(s):  
Phase Transitions ◽  
Temperature Dependence ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Molecular Motions ◽  
Isotropic Reorientation ◽  
Higher Temperature ◽  
Successive Phase

AbstractThe temperature dependence of 35C1, 81Br, and 127I NQR frequencies and 1Hspin-lattice relaxation times (T1) for CH3NH3PbX3 (X = Cl, Br, I) was measured through the successive phase transitions in these solids. The isotropic reorientation of the CH3NH3 ions takes place in the higher-temperature phases (tetragonal [I4/mcm] and cubic) of the three salts (Ea= 11 kJ mol -1). T1's in the lowest-temperature phases (orthorhombic) indicate that the cations undergo correlated C3-reorientation in the chloride (Ea = 5.45 kJ mol -1)and in the iodide (Ea = 5.80 kJ mol -1, whereas correlated (Ea = 2.40 kJ mol-1) and uncorrected (Ea = 7.50 kJ mol-1) C3- reorientations are excited in the bromide. It is also revealed that the rotational tunneling of the cations governs T1 at lowtemperature region in the orthorhombic phases of these salts

scholarly journals Raman study of phase transitions in compressed methane using moissanite anvil cells

2011 ◽  
Vol 84 (10) ◽  
Author(s):  
Pei-Nan Chen ◽  
Chang-Sheng Zha ◽  
Xiao-Jia Chen ◽  
Jinfu Shu ◽  
Russell J. Hemley ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Raman Study

X-ray diffraction and Raman study of DL-alanine at high pressure: revision of phase transitions

2012 ◽  
Vol 68 (4) ◽  
pp. 412-423 ◽  
Author(s):  
Nikolay A. Tumanov ◽  
Elena V. Boldyreva
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Structural Phase ◽  
Group Symmetry ◽  
Second Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Raman Study

The effect of pressure on DL-alanine has been studied by X-ray powder diffraction (up to 8.3 GPa), single-crystal X-ray diffraction and Raman spectroscopy (up to ∼ 6 GPa). No structural phase transitions have been observed. At ∼ 1.5–2 GPa, cell parameters b and c become accidentally equal to each other, but the space-group symmetry does not change. There is no phase transition between 1.7 and 2.3 GPa, contrary to what has been reported earlier [Belo et al. (2010). Vibr. Spectrosc. 54, 107–111]. The presence of the second phase transition, which was claimed to appear within the pressure range from 6.0 to 7.3 GPa (Belo et al., 2010), is also argued. The changes in the Raman spectra have been shown to be continuous in all the pressure ranges studied.

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